GB2288293A

GB2288293A - Circuit interrupter

Info

Publication number: GB2288293A
Application number: GB9505988A
Authority: GB
Inventors: Ping Zhen Hu; Hanns P Sailer; Esteban Santos
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1994-04-08
Filing date: 1995-03-24
Publication date: 1995-10-11
Anticipated expiration: 2015-03-24
Also published as: GB9505988D0; GB2288293B

Abstract

A circuit interrupter employs an electronic trip unit 1 having a keypad 4 and display 2 to enter and display stored trip parameters and trip data. The trip unit is powered by means of current transformer 7 before circuit interruption. Should overcurrent occur, the protected power circuit is interrupted and the battery 6 is immediately connected to the trip unit. The battery then provides energy to the trip unit's microprocessor and the display to provide visual indication as to the type and magnitude of the circuit interruption. <IMAGE>

Description

CIRCUIT INTERRUPTER The present invention relates to circuit interrupters.

Circuit interrupters employ a number of methods to store basic fault information for display to the operator. Some use mechanical targets while others use electrical targets such as LEDs or LCD segments. A mechanical target is actuated the same moment the interrupter is opened and stays in its actuated position until the customer resets it. The basic electronic target works in a similar manner. In one embodiment the LED is lit when the interrupter is tripped and then an auxiliary power source keeps the LED lit until the customer resets it. In a second method the target information (a single value) is stored in a non-volatile location for later viewing and resetting when power is reapplied to the programmer. In all known designs, one overriding factor was involved, the target information must be stored or presented before the primary power source shuts down.

In most interrupter designs; the primary power source is derived from current transformers. These provide the programmer with operating power as long as current flows through the interrupter. When a trip occurs, the current flow is stopped almost immediately, the power source decays rapidly and the programmer has very little time to store anything but the most basic fault information. This information is usually a single item such as type of trip (short circuit or overload).

The present invention seeks to provide an improved circuit interrupter of this type, and accordingly provides a circuit breaker interrupter comprising an electronic trip unit for determining occurrence of an overcurrent condition through a protected circuit; a keypad and a display on a surface of a circuit interrupter for entering overcurrent parameters to said trip unit and displaying such parameters upon request as well as displaying trip indication data; a pair of contacts controlled by an actuator connecting with said trip unit, said actuator driving said contact to an open condition upon receipt or a signal from said trip unit; a current transformer connecting with said protected circuit for supplying sample current to said trip unit and for providing operational power to said trip unit and display while said circuit is operational; and an auxiliary power source connecting with said trip unit for providing operating power to said trip unit and said display when said circuit is disconnected.

Such a circuit interrupter allows the programmer to store far more detailed trip information. For example, using a microprocessor controlled auxiliary power source such as a battery, when the microprocessor decides to trip the interrupter, it can, if desired, be arranged to switch over to the auxiliary power source. The programmer can then store far more detailed trip information including type of trip, the fault current at trip, time of trip, the phase the fault current appeared, etc. The programmer can also increment a counter to keep a historic record of how many trips the interrupter has experienced.

Once the needed trip information is stored away the microprocessor can shut the auxiliary power source down, thereby conserving its life for future use. Then at some later time the operator can query the programmer for the stored information.

The circuit interrupter may be arranged so the auxiliary power source is connected to the trip unit and display when the current transformer is not providing operational power to the trip unit and display and/or the auxiliary power source is disconnected from the trip unit and display when the current transformer is providing operational power to the trip unit and display.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying Figure 1 which is a schematic diagram of the embodiment.

Figure 1 shows an exemplary circuit interrupter according to the present invention which, as typical, contains at least one primary phase 9 that is being protected. A current transformer 7 provides the ability to both sense the magnitude of current flowing through the interrupter and provide a source of power for a programmer 1. The programmer 1 executes algorithms to determine whether to trip the interrupter. Should a decision be made to trip the interrupter, the programmer signals an actuator 5 to open the interrupter contacts.

The programmer then switches over to using the auxiliary power source, such as a battery 6 to store the needed trip information a memory 3 that does not lose information during power loss. The programmer itself shuts down. At some later point the operator can restore power to the programmer (by closing the breaker for example) and view the contents of memory on the display 2 using the keypad 4 to access the trip information.

Claims

1. A circuit interrupter comprising an electronic trip unit for determining occurrence of an overcurrent condition through a protected circuit; a keypad and a display on a surface of a circuit interrupter for entering overcurrent parameters to said trip unit and displaying such parameters upon request as well as displaying trip indication data; a pair of contacts controlled by an actuator connecting with said trip unit, said actuator driving said contact to an open condition upon receipt of a signal from said trip unit; a current transformer connecting with said protected circuit for supplying sample current to said trip unit and for providing operational power to said trip unit and display while said circuit is operational; and an auxiliary power source connecting with said trip unit for providing operating power to said trip unit and said display when said circuit is disconnected.

2. The circuit interrupter of Claim 1 wherein said trip unit includes a microprocessor.

3. The circuit interrupter of Claim 1 wherein said auxiliary power source comprises a battery.

4. The circuit interrupter of Claim 1 wherein said auxiliary power source is connected to said trip unit and display when said current transformer is not providing operational power to said trip unit and display.

5. The circuit interrupter of Claim 1 wherein said auxiliary power source is disconnected from said trip unit and display when said current transformer is providing operational power to said trip unit and display.

6. A circuit interrupter substantially as hereinbefore described with reference to the accompanying drawings.